1. Field of the Invention
The present invention relates to a rack shaft supporting apparatus supporting a rack shaft by a support yoke and a vehicle steering apparatus with the rack shaft supporting apparatus.
2. Description of the Related Art
It is well known in the prior art a vehicle steering apparatus in referring to FIG. 1 such as Japanese laid-open publication Tokkai 2005-41251.
The vehicle steering apparatus 900 includes a housing 901, a pinion shaft 902, a rack shaft 903, a rack and pinion mechanism 904 and a rack shaft supporting apparatus 910. The housing 901 accommodates a part of the pinion shaft 902, the rack shaft 903 and the rack shaft supporting apparatus 910. The rack and pinion mechanism 904 includes a pinion gear 902A of the pinion shaft 902 and a rack gear 903A of the rack shaft 903.
The rack shaft supporting apparatus includes a support yoke 911, a plug 912 and a coil spring 913. The plug 912 is fixed to the housing 901. The coil spring 913 imparts, to the support yoke 911, force pressing the support yoke 911 to the rack shaft 903.
The support yoke 911 includes a recess portion 911A having a shape corresponding to a shape of a back surface portion 903B of the rack shaft 903. The support yoke 911 includes a space 911B against the housing 901. The support yoke 911 supports the rack shaft 903 in a state that the rack shaft 901 is able to move along its axial direction.
In the rack shaft supporting apparatus 910, there is happened to create force rolling the rack shaft 903 along a longitudinal direction in accordance with rotation of the pinion shaft 902. The rolling is a rotational movement of a center axis of the rack shaft 903 along the longitudinal direction.
When the rack shaft 903 is rolled, the rack shaft 903 is received the force moving the rack shaft 903 against the pinion shaft 902 to a width direction of the rack shaft 903. As a result, the force along the width direction of the rack shaft 903 acts to the support yoke 911 supporting the back surface portion 903B of the rack shaft 903. Where an amount of the movement of the support yoke 911 is relatively large, there is created any contacting sound by contacting the support yoke 911 to the housing 901.
It is well known another prior art of a rack shaft supporting apparatus disclosed in U.S. Pat. No. 7,487,984 that a support yoke is pressed to a rack shaft through a rotating cam mechanism around a center axis of the support yoke by a torsion spring. In this another prior art, it happens the movement of the support yoke along a width direction of the rack shaft to create any contacting sound by contacting the support yoke to a housing.